linux-kernel - [PATCH] coresight: replicator: Reset replicator if context is lost

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Message-Id: <20200511083400.26554-1-saiprakash.ranjan@codeaurora.org>
Date:   Mon, 11 May 2020 14:04:00 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>
Cc:     Stephen Boyd <swboyd@...omium.org>, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, coresight@...ts.linaro.org,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Subject: [PATCH] coresight: replicator: Reset replicator if context is lost

On some QCOM SoCs, replicators in Always-On domain loses its
context as soon as the clock is disabled. Currently as a part
of pm_runtime workqueue, clock is disabled after the replicator
is initialized by amba_pm_runtime_suspend assuming that context
is not lost which is not true for replicators with such
limitations. Hence check the replicator idfilter registers
in dynamic_replicator_enable() and reset again.

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
---

More info here - https://lore.kernel.org/patchwork/patch/1231182/

---
 drivers/hwtracing/coresight/coresight-replicator.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-replicator.c b/drivers/hwtracing/coresight/coresight-replicator.c
index e7dc1c31d20d..11df63f51071 100644
--- a/drivers/hwtracing/coresight/coresight-replicator.c
+++ b/drivers/hwtracing/coresight/coresight-replicator.c
@@ -68,6 +68,17 @@ static int dynamic_replicator_enable(struct replicator_drvdata *drvdata,
 	int rc = 0;
 	u32 reg;
 
+	/*
+	 * On some QCOM SoCs with replicators in Always-On domain, disabling
+	 * clock will result in replicator losing its context. Currently
+	 * as a part of pm_runtime workqueue, amba_pm_runtime_suspend disables
+	 * clock assuming the context is not lost which is not true for cases
+	 * with hardware limitations as the above.
+	 */
+	if ((readl_relaxed(drvdata->base + REPLICATOR_IDFILTER0) == 0) &&
+	    (readl_relaxed(drvdata->base + REPLICATOR_IDFILTER1) == 0))
+		dynamic_replicator_reset(drvdata);
+
 	switch (outport) {
 	case 0:
 		reg = REPLICATOR_IDFILTER0;
-- 
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